1. Field of the Invention
The present invention relates to a novel improved color filter which is suitable for an image pickup apparatus using a solid state device such as a charge coupled device (CCD) or the like.
2. Description of the Prior Art
In case of using a solid state image pickup device such as a CCD or the like as an image pickup apparatus, the input video information is spatially sampled on the basis of a unit pixel of the image pickup device. Now, considering that a modulation signal (S.sub.DC) is modulated by a sampling frequency (f.sub.c), the reproducible modulation signal band becomes (1/2)f.sub.c as will be understood from the sampling theorem. Therefore, if the sampling frequency is insufficient for the modulation signal band, the side band component of the sampling frequency f.sub.c will be overlapped in the high frequency component S.sub.DH of the modulation component S.sub.DC as shown in FIG. 1. The hatched portion will become the fold-distortion, so that it is undesirable because a flickering phenomenon is caused in the reproduction picture image due to this.
As a method of removing this fold-distortion, for example, there is a method whereby a band width of the modulation component S.sub.DC is limited. However, this method is not so good since it causes the resolving power to deteriorate. In addition, although a method is considered whereby the sampling frequency is raised by increasing the number of pixels, this causes a problem such that the manufacturing yield decreases.